Forty years later, the idea of a homogenous "Eastern Europe" — grey, cowed, unsmiling, shabby, poor, backward and isolated — had taken deep root in outsiders' minds. In meticulous, gripping, poignant detail, Iron Curtain explains how that came about. It sustains a narrative arc over 11 years in multiple countries, while dealing with names, places and events that to many readers will be unfamiliar. 

She roots the story in the chaos of the immediate postwar era. It may come as a surprise to British readers, for example, to know that the fighting did not stop in 1945. Many countries were in a state of, in effect, civil war, with the remnants of wartime anti-Communist resistance armies (in Poland's case under the command of the lawful government-in-exile in London) fighting the invaders from the east. The last Polish fighter, Józef Franczak, was killed in an ambush in 1963. The last Estonian partisan, August Sabbe, died while fleeing the KGB as late as 1978.

With memories of the chaos of war still raw, Communist rule seemed to many less horrific at the time than it does in retrospect. For all the iniquity of the Molotov-Ribbentrop Pact of 1939, in which Stalin teamed up with Hitler to divide the region, the Soviet Union and Communism had acquired a kind of moral legitimacy. Capitalism and bourgeois democracy seemed to have failed catastrophically. The Soviet Union had redeemed itself through the defeat of Fascism. Was it not time to give something else a try?

Though the process was eventually barbaric and ruthless, everything did not happen at once. Just as with the Bolshevik Revolution 30 years earlier, the Communists did not begin with a blueprint. They made it up as they went along. They did not start off believing that a general policy of savagery would be necessary. 

Our recent memory of Communism is shaped by its declining years, when debts, strikes and shortages highlighted the unworkability of planned economies. But the commissars of 1945, a rum lot with murky backgrounds and varying abilities, believed their own propaganda. It might be necessary to act toughly against individual enemies, with murder, torture, imprisonment or blackmail. Rivals for power — such as non-Communist political parties — were fair game too. But the Communists did not believe it would be necessary to impose their rule by terror. Explained properly, and given enough time, the masses would vote for it anyway.